Allegheny County, Pennsylvania
The dominant drainage class is Well drained and the dominant hydrologic group is C (slow infiltration, moderate runoff). This report summarizes the major soil map units across the survey area to help you understand what to expect when buying, building, or gardening in Allegheny County, Pennsylvania.
| Soil Map Unit | Acres | Drainage | Hydro Group | Dwellings | Septic |
|---|---|---|---|---|---|
| Gilpin-Upshur complex, very steep | 51K | Well drained | C | Very limited | Very limited |
| Gilpin, Weikert, Culleoka channery silt loams and 25 to 80 percent slopes | 47K | Well drained | C | Very limited | Very limited |
| Urban land-Culleoka complex, moderately steep | 24K | Not rated | Not rated | ||
| Urban land | 21K | Not rated | Not rated | ||
| Urban land-Rainsboro complex, gently sloping | 19K | Not limited | Not limited | ||
| Dormont silt loam, 8 to 15 percent slopes | 17K | Moderately well drained | D | Somewhat limited | Very limited |
| Gilpin silt loam, 15 to 25 percent slopes | 16K | Well drained | C | Very limited | Very limited |
| Wharton silt loam, 8 to 15 percent slopes | 13K | Moderately well drained | C/D | Very limited | Very limited |
| Dormont silt loam, 15 to 25 percent slopes | 13K | Moderately well drained | D | Very limited | Very limited |
| Urban land-Culleoka complex, gently sloping | 13K | Not rated | Not rated | ||
| Gilpin-Upshur complex, 15 to 25 percent slopes | 13K | Well drained | C | Very limited | Very limited |
| Urban land-Guernsey complex, moderately steep | 12K | Very limited | Very limited | ||
| Wharton silt loam, 3 to 8 percent slopes | 12K | Moderately well drained | C/D | Very limited | Very limited |
| Rayne silt loam, Conemaugh geology, 8 to 15 percent slopes | 11K | Well drained | B | Somewhat limited | Somewhat limited |
| Strip mines, 8 to 25 percent slopes | 10K | Well drained | C | Somewhat limited | Very limited |
| Water | 10K | Not rated | Not rated | ||
| Atkins silt loam, 0 to 3 percent slopes, frequently flooded | 8K | Poorly drained | B/D | Very limited | Very limited |
| Culleoka channery silt loam, 15 to 25 percent slopes | 8K | Well drained | B | Very limited | Very limited |
| Urban land-Culleoka complex, steep | 8K | Very limited | Very limited | ||
| Dormont silt loam, 3 to 8 percent slopes | 7K | Moderately well drained | D | Somewhat limited | Very limited |
What This Means
Building & Foundations
About 60% of soils are rated "very limited" for dwellings with basements. Specific challenges include shallow bedrock, steep slopes, poor drainage in some areas, flood-prone areas. A geotechnical assessment is recommended before building.
Septic Systems
About 71% of soils are rated "very limited" for septic absorption fields. Despite good drainage overall, limitations may stem from shallow bedrock, steep slopes, or seasonal conditions. Engineered or alternative systems are frequently required. Always get a professional perc test before purchasing land that needs septic.
Gardening & Agriculture
Well-drained soils on sloped terrain — good for most plants but watch for erosion. Terracing, contour planting, and mulching help retain moisture and topsoil. Drip irrigation is more effective than sprinklers on slopes.